The present invention relates to a drainage hole structure in an oven of forced convection type.
Conventionally, wide variety kinds of heating apparatuses including a microwave oven, a microwave heating oven or the like, have been developed and used. Some of them employ a certain kind of heating chamber in which a hot air is circulated and to which a positive pressure is applied, and they are represented by, for example, a cooking apparatus of forced convection type and a cooking apparatus utilizing impingement heat jet heating. Further, some of them employ such heating chambers into which water, hot water, steam or the like are introduced, and they are represented by, for example, a steamer and a complex heating oven of forced convection type added with a steaming function or a steamer.
In an oven of forced convection type (hereafter those cooking apparatuses as described above generally referred to as the ovens of forced convection type), particularly in a case where water, hot water, steam or the like are introduced into a heating chamber for cooking or cleaning, a drainage hole must be provided.
Since when the drainage hole in the heating chamber is open to the atmosphere, a heat (an air) leaks to the outside thus to cause an energy loss and a thermal affection to the circumstance, therefore such a drainage hole structure in which the drainage hole is equipped with a lid in order to prevent such air leakage has been employed. However, such structure employing the lid has exhibited the following problems. That is, dirt, which has been accumulated, makes it difficult for the lid to be taken out. In addition, a care must be taken to accomplish air tightness. Further, during the lid being taken out, a trouble might be caused associated with the handling of this removed lid. For example, a care must be taken in order to keep the removed lid without missing it.
In another drainage hole structure according to the prior art, a drainage hole has been provided with a valve, such as a ball valve, an electromagnetic valve or the like. However, the structure employing such a valve also has exhibited the following problems. That is, because there is a valve mechanism in a drainage path, dirt is likely to be accumulated and the cleaning is difficult to be conducted therein. The accumulated dirt obstructs a regular operation of the valve, which is likely to result in a break down. A care must be taken also to accomplish a heat resisting of a valve sealing portion.
An object of the present invention is to provide a drainage hole structure in an oven of forced convection type, which can solve the problems associated with the prior technology as described above.
A drainage hole structure in a cooking oven of forced convection type according to the present invention comprises: a drain pipe arranged so that an upper end opening thereof is open to a bottom face portion of a heating chamber and a lower end opening thereof is open to the outside of said heating chamber; and an air suction pipe arranged so that one end opening thereof faces to said upper end opening of said drain pipe in close proximity thereto and the other end opening thereof is open to a middle portion in said heating chamber; wherein said one end opening of said air suction pipe is formed to be slightly larger than said upper end opening of said drain pipe; and, in said upper end opening side of said drain pipe, a peripheral wall portion of said drain pipe positioned in an upstream side with respect to an airflow flowing along the bottom face portion of said heating chamber is extended so as to enter into said one end opening of said air suction pipe by only a short distance, while a peripheral wall portion of said drain pipe positioned in a downstream side with respect to the airflow flowing along the bottom face portion of said heating chamber is terminated at a level substantially equal to or lower than said bottom face portion of said heating chamber.
According to an embodiment of the present invention, said upper end opening of said drain pipe is located in close proximity to an air blowing side of a fan used for a forced convection, which is arranged in a back face side of said heating chamber, and said other end opening of said air suction pipe is located in close proximity to an air suction side of said fan.
According to another embodiment of the present invention, said air suction pipe is integrated with a fan guard which is to be disposed in front of said fan.